Habitat Selection and Ecological Separation between Sympatric Tibetan Argali and Blue Sheep

Abstract

"Summer habitat utilisation and ecological separation between the sympatric mountain ungulates Tibetan argali Ovis ammon hodgsoni and blue sheep Pseudois nayaur in Hemis High Altitude National Park, Ladakh, India were studied to determine how the two species coexist. I investigated the hypothesis that ecological separation between the blue sheep and Tibetan argali occurs on the basis of physical habitat selection. Such separation was tested for on the basis of expected difference between the species, as related to proximity to cliffs associated with the species-specific anti-predator behaviour. Tibetan argali selected habitats away from cliffs while blue sheep selected habitats close to cliffs. Blue sheep also selected steep slopes whereas argali selected gentle slopes. Slope angle was found to be more important than distance to cliff in shaping the niche relationship. The two species did not differ in their use of habitats in terms of elevation and vegetation cover. They however differed in their use of plant communities; blue sheep selected sub-shrub and grass communities whilst argali selected forb communities. The two species are ecologically separated on the basis of physical habitat (and perhaps food), and presumably do not compete for common resources."